This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. sp56 is a rodent specfic sperm protein that binds to ZP3 on the egg cell surface in mice. We have predicted a human ortholog of sp56 that is located in the same syntenic block as mouse sp56. We have confirmed that human sp56 is expressed by RT-PCR and now want to confirm that the translated protein is present in human sperm by mass spec. To prepare the samples, we pelleted sperm from human seminal fluid and solubilized the sperm proteins by boiling them in either SDS or RapiGest. We searched the resulting spectra against the human database containing our predicted sp56 gene to confirm protein presence.